This investigation will establish a multicenter, randomized clinical trial to evaluate the long-term safety and efficacy of usual medical therapy alone vs. usual medical therapy and lung volume reduction therapy (LVRS) for moderate to severe emphysema. The primary objectives are to determine if the addition of LVRS to medical therapy improves survival and increases exercise capacity. Secondary objectives are to define the profile of patients likely to benefit most, and to determine if LVRS improves quality of life, reduces symptoms, etc.